This blog is devoted to the application of optical fibers in photography. I have several homemade (DIY) flash adapters channeling the light from the flash close to the lens. The technique can be used mainly for macro photography, but I will show examples for wide angle close focus techniques as well. The recent version is called fiberstrobe V3, hence the name of the blog is "fiberstrobe".

Sunday, May 1, 2011

How to build a ring-flash adapter

There are many good optical fiber-based DIY ringflash adapters. For examples see the following links:

However, I found a bit their installation a bit complicated. To make such adapter more user-friendly I built the whole concept around a tube that can be slide around the lens. Below I provide a tutorial on how I built my ringflash adapter for sony nex-5. You can follow the same principle to build your own for any camera type.
I bought a plastic waterpipe in the local hardware store. I used 75 mm diameter tube, but you should consider that there is an effective subject to flash (here adapter) distance for ringflash work. It's approximately between the half of the diameter and twice the diameter of the ring. So the optimum for my adapter is between 4 and 15 cm. For 100 mm macro lens with longer subject to lens distance you have to use larger diameter tubes.
I cut a 10 cm piece with fretsaw:

I glued plastic-foam pieces into the inner part of the tube to hold it firmly around the lens. This way I can easily slide the tube to the lens:

For this adapter I used 36 pieces of 1mm diameter optical fibers but the 0.75mm one would have worked better. The length varied according to the placement of the end of the filament. I cut 3 little pieces of velcro stripe (hooked one, 25mm according to the opening of the flash) and glued 12 fibers into each leaving some overhangs:

Then I prepared the part mounting the end of the fibers to the flash. For this I used a plastic bag lock (I don't know the proper English term, I found this in the kitchen. Aluminium folie was used as spacer).

I glued the three velcro stripes together and fitted the fibers through the plastic mount and glued it (you have to use a special glue not dissolving the fibers. I used a polystyrol glue from pattex). Later on I trimmed back the overhangs and polished them.

The next step is the fixing of the end of the fibers to the tube. I cut a velcro stripe (hooked one) encircling the tube into 4 equal pieces and fitted the fibers in between the hooks spacing them more or less equual distance. The stripe going to the below part of the tube was further cut into two pieces:

The velcro stripes were stuck to the tube (I used a self-adhesive type of velcro) and they were further fixed with duck tape. I still don't have a good solution how to attach the end of the fibers to the flash. I glued two layers from the plastic foam panel also used for the inner part of the tube to provide support at the proper height. After bending the bunch of the fibers (with the help of a hair drier, use it carefully!!) I glued the end fitting on the top of these foam pieces and further fixed it with duck tape.

The flash adapter works well but the sony nex flash is really weak. It has a guide number of 7, but still at ISO400 I can use f16 most of time (depending on the distance and the colour of the subject).
For results, see my flickr page:http://www.flickr.com/photos/fiberstrobe/sets/72157626491664288/
If you have any question or suggestions, don' hesitate to contact me. You can also send me picures of your own version, I will post it on my blog.
Have a good tinkering.

Good luck and please report back about your project. I highly recommend to make your adapter for the new hvl-f20s flash. The small flash coming with the nex is just too weak. I wrote about it here:http://www.fiberstrobe.blogspot.de/2012/07/ringflash-adapter-re-loaded.htmlAnd use more fibers.